The present invention relates to an electric control apparatus for processing data measured with various sensors and controlling an engine and/or suspension of an automobile on the basis of the processed data, and more particularly to an apparatus for and method of compensating for a time delay of measured data.
In a conventional electric control apparatus for an engine and/or suspension of a vehicle, such as an automobile, data measured with various sensors is picked up at an interval of a constant time or constant rotary angle (i.e., rotary angle of the crank shaft), and the picked up data is averaged, e.g., by means of weighted averaging, within a predetermined section (e.g., within a predetermined time duration or predetermined rotary angle range), and is processed for removal of noises by means of a primary delay filter or the like, to effect smoothing of pulsation of suction air to the engine, and to other processings. The electric control apparatus of this type is disclosed in, e.g., Japanese Patent Laid-open Publication JP-A-58-8239.
The engine conditions of an automobile change from time to time while measuring engine running data. Therefore, it becomes necessary to control fuel injection, ignition advance angle and the like in order to deal with such a change, especially a rapid change of the engine conditions. However, the control operation will be delayed due to a time delay at a filter used for noise removal, a time delay at a sensor while converting a physical value into an electrical value, and a time delay required for processing data at the electrical control apparatus of is automobile.
Such a delay in the control operation will be described with reference to FIGS. 1 and 2. FIG. 1 is a graph showing a relationship between a throttle opening angle (degree) of a throttle valve and a flow rate Q of suction air to the engine, and FIG. 2 is a graph showing the control characteristic of an air/fuel ratio of a gas mixture in the engine when rapidly opening the throttle valve under control of a conventional control apparatus.
FIG. 1 shows a characteristic curve (a) of measured data obtained when rapidly opening a throttle valve as shown by a curve (c), wherein the flow rate of suction air to the engine is measured with an air flow sensor, such as a hot-wire type air flow meter, and the measured data is passed through a filter, such as an RC circuit, in the manner as will be described later and thereafter A/D converted. A curve (b) represents an actual flow rate of suction air to the engine. It is to be noted that the measured data exhibits a delay from the actual flow rate because of a delay in the air flow meter, RC circuit and the like. Therefore, if a fuel corresponding in amount to an air flow rate measured at the time of rapid opening of the throttle valve is injected for the purpose of obtaining a target air/fuel ratio, e.g., of 14.7, the resultant air/fuel ratio takes a value shifted from the target value 14.7 as shown in FIG. 2 because of a delay of the measured air flow rate. Therefore, there arises the phenomenon that the air flow rate becomes lean at the start of acceleration (at the time of increasing the air flow rate), whereas it becomes rich during a short period at the end of acceleration.
As described above, there arises the problem that a correct control cannot be ensured during a rapid engine condition change if actuators (e.g., the fuel injection valve and the like) are controlled in accordance with manipulatory values calculated based on the averaged or smoothed, measured data.
As disclosed in Japanese Patent Laid-open Publications JP-A-63-131840 and JP-A-63-131841, in an engine control apparatus which calculates a fuel injection time on the basis of an output from a pressure sensor for measuring the pressure in an intake tube, the pulsation component of a pressure output signal from the pressure sensor is removed with a filter having a relatively large time constant. In order to compensate for a delay of the fuel injection control caused by a delay of the measured pressure data, a reference fuel injection time duration at a current time point is adjusted based on a difference between the reference fuel injection time duration at the current time point and the reference fuel injection time duration calculated one period earlier, and based on other parameters. A fuel injection time duration is calculated based on the data supplied from a plurality of sensors, such as pressure sensor data, engine revolution number data and the like. However, this control apparatus operates to compensate for a time delay not of the respective measured data, but of the final manipulatory value. Therefore, the control apparatus cannot satisfactorily follow a rapid change in output data from respective sensors so that the delays in measured data cannot be correctly compensated. For example, in the case where only the pressure in the intake valve changes and the engine rotation number does not change, it is not possible to compensate for the measured pressure data only. Consequently, a correct engine control is not possible leading to a hardship of proper engine output control and exhaust gas control.
Further, there is not known a conventional electric control apparatus for a suspension which can compensate for a delay of measured data from a dumper stroke sensor or the like, resulting in a hardship of correctly controlling a suspension upon a rapid change of road conditions.